The proteins actin, myosin and troponin have been isolated from mammalian brain. The objectives of this proposal are to continue our studies on the isolation, purification, and biochemical and physical characterization of these proteins isolated from bovine or rat brain. These studies include SDS-polyacrylamide gel electrophoresis, amino acid composition, enzyme kinetics and electron microscopic examination in organotypic cultures. The troponin-complex will be isolated, dissociated into its components and compared with their counterparts isolated from rabbit striated muscle.